In some instances, it may be important for a network administrator to determine the topology an optical network. For example, it may be helpful for the network administrator to determine that an optical fiber connects a given port of one device in the optical network to a given port of another device in the optical network. Knowledge of the topology of the optical network may be helpful when establishing routes through the optical network, diagnosing and remedying problems in the optical network, and performing other manual or automated network management tasks.
For example, an optical network may include a router, a multiplexer/demultiplexer (Mux/Demux), and a reconfigurable optical add-drop multiplexer (ROADM). The connections of these devices can involve about 400 touch points for 100 different wavelengths. In known optical networks, the access link is manually provisioned. In addition, in case of misconnection or misconfiguration, usually no mechanism exists to identify the root cause. Moreover, routers and ROADMs typically use different command line interface (CLI) dialects, thereby rendering the correlation of relevant information challenging.
Another approach to determine the topologies of optical networks uses a device sending wavelength-modulated optical signals on various ports of the device. The wavelength-modulated optical signal sent on a given port of the sending device is encoded with identification information specific to the given port. If a device receives the modulated optical signal on a given port, the receiving device demodulates the optical signal and outputs a report message to a network management system (NMS). The report message indicates the source of the received signal. The NMS may use such messages to generate topology data for the optical network. A problem with this approach is that the receiving device includes hardware to demodulate the optical signal and such hardware may be complex and expensive, thereby increasing the cost of the resulting optical network.